Arc chute



J. D. WOOD ARC CHUTE April 26, 1949.

Filed June 20,1945

2 Sheets-Sheet l ATTORNEYS J. D. WOOD April 26, 1949.

ARC CHUTE 2 Sheets-Sheet 2 Filed June 20, 1945 INVENTOR. Joseph D.Wood BY ATTORNEYS Patented Apr. 26, 1949 ARC CHUTE Joseph D. Wood, Upper Darby, Pa., assignor to I. T. E. Circuit Breaker Company, Philadelphia, Pa., a corporation of Pennsylvania Application June 20,1945. Serial No. 660,554

4 Claims.

My present invention relates to circuit interrupters and more particularly to arc extinguishing means therefor adapted to rapidly cool and extinguish an are drawn between the contacts when they separate.

Essentially my novel are chute is a composite structure of intersecting metallic and insulating plates comprising a stack of spaced metallic plates arranged parallel to each other and transverse to the path of the arc; this stack of plates is combined with and intersected by another stack of plates of insulating material arranged parallel to each other and parallel to the path of movement of the arc.

Each of the metallic plates may have a notch, the notches in the plates being aligned with each other and directed toward the area where the arc is first drawn. The are is driven into the notched area and then between the metallic plates and broken up in series as it is moved rapidly up on the plates; the series arcs are then compressed laterally between the insulating plates as the small series arcs are driven further away from the contacts.

In order to provide this type of arc extinguishing structure with one set of plates intersecting another set of plates, one set of plates is notched to receive the other set, or the two sets of plates are complementarily notched so that they may interengage each other and form substantially a plurality of cells, each cell having two metallic walls and two insulating walls at the upper or outer end of the arc chute.

A principal object of my invention, therefore, is the provision of a novel are extinguisher having a plurality of parallel arc extinguishing plates intersected by another set of spaced arc extinguishing plates normal thereto.

Another object of my invention is the arrange ment of an arc extinguisher so that a set of spaced metallic arc extinguishing plates is intersected by a set of spaced insulating are extinguishing plates.

Another object of my invention is the formation of an arc extinguisher having a plurality of spaced parallel plates for first intercepting the arc, the arc extinguisher also having a section comprising a plurality of cells for further cooling, confining and extinguishing an arc.

Another object of my invention is the provision of an arc extinguisher so that the stack of spaced metallic plates first intercepts the arc and breaks it up in series among the plates, the said metallic plates being intersected by another stack of insulating plates which confines the individual series arcs laterally.

The foregoing and many other objects of my invention will become apparent in the following description and drawings in which Figure 1 is a view in perspective showing a circuit interrupter having my novel are extingisher.

Figure 2 is a view in perspective showing a slightly modified arc extinguisher.

Figure 3 is an expanded view showing the manner in which the insulating and metallic plates are arranged to intersect each other.

Figure 4 is a plan view of one of the metallic plates of the arc extinguisher of Figure 2.

Referring now to Figure 1, I have here shown a circuit interrupter having a housing II including a back wall H on which is mounted a stationary contact I3 secured to a connecting plate 14, which connecting plate i4 is bent up to form the terminal l5. Movable contact 16 is mounted on a contact lever H which is carried by the contact arm I8 secured to the rotatable shaft 19. Rotatable shaft I9 is operated in a counterclockwise direction to close contacts l6 and 13 in a clockwise direction to open contacts I6 and I3.

Any suitable operating mechanism may be used for operating contact arm 18 and since such operating mechanism may take many forms, a specific operating mechanism is not shown.

Contact lever I1 is connected by the pigtail 20 to the lower terminal 2|. Current thus passes from terminal to plate II to stationary contact [3 to movable contact l6 through the contact lever I"! to pigtail to the lower terminal 2 I.

The are chute 22 is generally of the type described in Patent No. 2,244,061, issued June 3, 1941 to Herbert C. Graves, Jr., and assigned to the assignee of the present invention, and comprises a pair of side walls 23, 24 of insulating material preferably vulcanized fibre, each of the side walls 23, 24 having a re-entrant flange 25 defining a pocket 26 to receive the legs 21, 28 (Figure 4) of the spaced metallic plates 29.

Figure 4 has here been referred to since it illustrates the general shape of the plates 29 of Figure 1. The Figure 4 plate, however, is particularly adapted for use with the Figure 2 arc chute construction. The only difference between the plate of Figure 4 and the plates 29 of Figure l is that plates 29 of Figure 1 are longer.

Adjacent plates in the stack are reversed with respect to each other so that the notches 30 thereof are slightly out of alignment in order to assist further in driving the are between the plates.

Each of the legs 28 is provided with an extension 3| (see Figure 4 as well as Figure 1) defining a recess 32 for receiving the end of the re-entrant flange while the leg is received in the pocket 26.

The plates 29 are supported between the side walls 23, 24 by lugs 32 passing through slots in the side walls, the lugs being twisted after having been passed through the slots in the side walls 23, 24 in order to hold the plates 29 in position.

The top wall of the arc extinguisher comprises an insulating plate 35 secured in any suitable manner to the top ends of the side walls 23, 24, the said top wall being provided with appropriate openings to permit the arc gases to escape.

The lowest plate 36 in the arc extinguisher is in contact with the connecting plate I4 and acts as a lower arcing horn connected to the stationary contact l3. A top metallic plate 31, preferably of iron, is also provided, the said plate carrying an arc horn 38.

Movable contact it; moves into close juxtaposition with the arc horn 38 when the contacts open so that the arc is driven up between arc horn 38 and the plate 31 at the front of the arc extinguisher and plate 36 at the back of the arc extinguisher.

The entire circuit breaker is here' shown in horizontal form for convenience; it is usually mounted so that plate 35 is at the top and terminal 2| at the bottom.

Each of the plates 29 is at its upper end provided with a plurality of notches 40, the notches 40 in each plate being aligned with each other. Each set of aligned notches 40 is arranged to receive an insulating plate 4|, the said insulating plates 4|, 4| being inserted from the top of the arc extinguisher after the plates 29 are mounted between the said plates 23 and 24 and before the top plate 35 is secured in position.

Top plate 35 when in position then secures the insulating plates 4| in the aligned notches 40. This securement is obtained because the top plate 35 is finally secured in position by the lugs 43 of the metallic plates 29 (see also Figure 4) which extend through appropriate slots in the top plate 35 and are twisted after having passed therethrough for firm securement of the top plate 35.

It will thus be seen that when the arc is first drawn on separation of contacts l3 and IE, it is moved up into the arc chute along arc horn 38-31 and are horn 36 into the stock of plates 29. On entering the stack of plates 29 and moving upwardly therein, the arc is broken up in series among the plates. As the arc moves further upwardly in the arc extinguisher, the series arcs moving along the plates 29 now move between the parallel insulating plates 40 and are squeezed therebetween and are thus rapidly extinguished.

Thus. the combined action of a stack of metallic plates which intercepts the arc and breaks it up in series and a plurality of insulating plates parallel to the arc is obtained leading to more rapid and more effective extinguishment of the arc.

In effect, therefore, the lower portion of the arc chute comprises a plurality of spaced metallic plates which intercept the arc and break it up in series and the upper portion of the arc chute comprises a plurality of cells, each cell having a pair of metallic walls and a pair of insulating walls for further confining and extinguishing each of the small series arcs.

The action of the arc chute thus shown is a composite of the action of the arc chute shown in Patent No. 2,244,061 issued June 3, 1941,; to Herbert C. Graves, Jr. and in Patent N0. 2,338,715 issued January 11, 1944, to Herbert C. Graves, Jr., both of which are assigned to the assignee hereof. It will be obvious that the ends of the plates 4| directed toward the arc may be cusped, curved, notched or otherwise shaped in any desired manner to assist in the arc extinguishing operation, and the notches 40 in the plates 29 may be of an appropriate length in each plate to closely engage the said edges of the insulating plates 4|.

In Figure 2 I have shown a slight modification of the arc extinguisher of Figure 1, wherein the same combination of metallic and insulating plates is shown, but wherein the structure is adapted for use in connection with are chute elements which have already been fabricated.

The plates 29a have the form shown in Figure 4 and are more specifically described in connection with Figure 1. They are mounted in the housing 22a between the side walls 23a and 24a in the same manner, the legs 21 and 28 entering into the pockets 26a formed by the re-entrant flanges 25a of the side walls. These plates 29a have the form and size of plates previously used in arc extinguishers particularly the type shown in the above mentioned Patent No. 2,244,061. However, the arc chute housing 22a is modified by extending the walls 23a and 24a upwardly for a greater distance to include the additional arc extinguishing assembly 5|].

The additional arc extinguishing assembly comprises a plurality of substantially rectangular metallic plates 5| in spaced relation to each other and arranged to intercept the arc, the plates 5| being intersected by a plurality of spaced parallel insulating plates 52.

The lower end 53 of each of the plates 5| (Figure 3) is provided with a plurality of notches 54, 54 equal in number to the number of insulat ing plates 52 which are to be used. the rows of notches in the stack of plates 5| being aligned with each other to receive the insulating plates 52.

The upper edges 55 of the insulating plates 52 are each provided with a plurality of notches 58, 56, the number of notches 56 being equal to that of the plates 5|. The plates 52 are fitted together with plates 5| by sliding notches 56 of plates 52 with respect to the aligned notches 54 of plates 5| to produce the cellular stack 59 shown in Figure 2.

This integrated stack is secured in position between the side walls 23a and 24a by lugs 32a extending from the side edges of plates 5| passing through openings in the side walls 24a and 23a and twisted after having passed through the openings.

Top wall 35a is held in position by lugs 43a of plates 5| which pass through appropriate openings in the top wall 35a and are twisted after having passed through the openings.

The are extinguishing stack 50 as seen in Figure 2 is arranged above the arc extinguishing stack of plates 29a. The plates 5| may be aligned with and may constitute substantial continuations of plates 290. It may be preferred, however. to arrange the plates 5| so that they extend in planes between the planes of adjacent plates 2911 so that the series arcs will be intercepted substantially at their centers by the lower edges of the plates 5|.

The stack 50 thus comprises a substantially cellular structure in which each cell has a pair of metallic walls and a pair of insulating walls, the metallic walls breaking the arc up in series and the insulating walls confining the arc.

By the means thus shown in Figures 1 and 2, a composite arc chute is provided which performs a double function. In prior arc extinguishers, the arc could be broken up in series by a plurality of plates which intercept the are or alternatively it could be confined between parallel plates. By means of my novel invention, the arc may both be broken up serially and confined by parallel walls.

While in the composite structure it is preferable that the plates which first intercept the are be of metallic material and the plates which extend parallel to the are be of insulating material, it will be' obvious that in appropriate cases both sets of plates may be of insulating material. In this latter instance, the arc would be extended into a sinusoidal form rather than broken up serially while the extended sinusoidal arc would be confined and squeezed by the parallel plates.

While I have shown the arc extinguisher so arranged that the plates which intercept the are have edges extending closer to the area where the arc is drawn than the edges of the plates which are parallel to the arc, it will be obvious that the arc chute may be arranged so that the lower edges of the plates are aligned with each other. This is entirely feasible as shown by the stack 50 'of Figure 2 and it is obvious that the lower edges of the stack 59 of Figure 2 may be modified to have any appropriate shape-the plate edges defining for instance, a concave or convex form, which concave or convex form may have any appropriate shape, including spherical or conical shapes and modifications thereof.

In this case the stack 59 thus modified may readily be used as an arc extin hed when appropriately mounted with respect to the contacts between which the arc is drawn.

In the foregoing I have described my invention only in connection with an illustrative embodiment thereof. Since many modifications and variations of my invention will now be apparent to those skilled in the art, I prefer to be bound not by the specific descriptions herein but only by the appended claims.

I claimi 1. In a circuit breaker having a movable and a complementary contact, said movable contact being movable to engaged and disengaged positions with respect to said complementary contact, an arc extinguisher comprising a first set of spaced metallic plates parallel to each other and another set of spaced insulating plates normal to said first set of spaced plates, said metallic plates being substantially parallel to each other and extending in planes transverse to the path of movement of the movable contact and to the are drawn between said contacts when they separate so that as the arc is moved into the arc chute formed by said plates, the arc is broken up into a series of arcs and as the series arcs move further into the arc chute they move between the insulating plates and are squeezed therebetween.

2. In a circuit breaker having a movable and a complementary contact, said movable contact being movable to engaged and disengaged positions with respect to said complementary contact, an arc extinguisher comprising a. first set of spaced metallic plates parallel to each other and another set of spaced insulating plates normal to said first set of spaced plates, and intersecting said first set of spaced plates, the lower portion of the arc chute formed by said plates comprising said plurality of spaced metallic plates, said metallic plates being substantially parallel to each other and extending in planes transverse to the path of movement of the movable contact and to the are drawn between said contacts when they separate so as to intercept the arc and break it up into a small series of arcs and the upper portion of the arc chute comprising a plurality of cells, each cell having a pair of metallic walls and including said insulating plates for confining and extinguishing the small series are.

3. In a circuit breaker having a fixed and movable contact, an arc extinguisher comprising a first set of spaced metallic plates parallel to each other and transverse to the are formed when said contacts separate and another. set of insulating spaced plates normal to said first set of metallic spaced plates, and intersecting said first set of spaced plates to form a plurality of arc confining cells, at least one of said metallic plates being of magnetic material.

4. In a circuit breaker having a movable and a complementary contact, said movable contact being movable to engaged and disengaged positions with respect to said complementary contact, an arc extinguisher comprising a first set of spaced metallic plates parallel to each other and another set of spaced insulating plates normal to said first set of spaced plates, and intersecting said first set of spaced plates to form a plurality of arc confining cells; each cell having a pair of insulating walls and a pair of metallic walls, said metallic plates being substantially parallel to each other and extending in planes transverse to the path of movement of the movable contact and to the are drawn between said contacts when they separate so that as the arc is moved into the arc chute formed by said plates, the arc is broken up into a series of arcs and as the series arcs move further into the arc chute they move between the insulating plates and are squeezed therebetween.

JOSEPH D. WOOD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

